geomtransf of bracing elements

[soraya]

Hi all,
I want to model a 3D steel braced building with concentric X bracing in both directions.
I am defining beams in X direction, Girders in Z direction and columns in Y direction.

I have problem for defining transformation of bracing elements.

geomTransf Linear $IDbrace45degreeXdir 0 0 -1;
geomTransf Linear $IDbrace135degreeXdir 0 0 1;
geomTransf Linear $IDbrace45degreeZdir -1 0 0;
geomTransf Linear $IDbrace135degreeZdir 1 0 0;

Are these correct?

[MohsenShani]

It depends on your section of direction. Would help, please contact me by email

civilshani@yahoo.com
Ali Shauni

[ejpirouz]

Dear all
Hello,
Recently, I have been reviewing the forum on how to properly define geometric transformation for bracing elements in 3D modeling. In my research i found that mostly the Vecxz for bracing elements are defined as if they are oriented along one of 3 Cartesian axes (e.g. 1 0 0, or 0 0 1 ...). This has become ambiguous for me since bracing elements mostly placed at an angle with respect to Cartesian axes (e.g. theta), and it is expected that the geomTransf be for instance (sin(theta), cos(theta), 0).
I would really appreciate if one could made it clear and correct my point of view.
Best Regards.

[fmk]

the geometricTransformation vector in 3d defines the xz PLANE .. it is not the z direction and therefore does not have to be perpendicular to the x dirn .. a picture is worth a thousand words: http://opensees.berkeley.edu/wiki/index ... sformation

[ejpirouz]

Dear fmk
Hello,
Thank you for your time and answer.
I was wondering whether, provided that the geometricTransformation vector in 3d defines the X-Z Plane, one could say there would be no difference between geomTransf of two elements with different Local axes' angle with respect to Global axes, as long as both Local X-Z plane are placed parallel?
Thank you in advance.

[fmk]

as long as the local axis and this new vector define the same xz plane.